Inhibition of ABL1 tyrosine kinase reduces HTLV-1 proviral loads in peripheral blood mononuclear cells from patients with HTLV-1-associated myelopathy/tropical spastic paraparesis

Human T-cell leukemia virus type 1 (HTLV-1) causes incurable adult T-cell leukemia and HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). Patients with HAM/TSP have increased levels of HTLV-1-infected cells compared with asymptomatic HTLV-1 carriers. However, the roles of cellular genes in HTLV-1-infected CD4+ T cells await discovery. We performed microarray analysis of CD4+ T cells from HAM/TSP patients and found that the ABL1 is an important gene in HAM/TSP. ABL1 is a known survival factor for T- and B-lymphocytes and is part of the fused gene (BCR-ABL) known to be responsible for chronic myelogenous leukemia (CML). ABL1 tyrosine kinase inhibitors (TKIs), including imatinib, nilotinib, and dasatinib, are used clinically for treating CML. To evaluate whether ABL1 is indeed important for HAM/TSP, we investigated the effect of TKIs on HTLV-1-infected cells. We developed a propidium monoazide-HTLV-1 viability quantitative PCR assay, which distinguishes DNA from live cells and dead cells. Using this method, we were able to measure the HTLV-1 proviral load (PVL) in live cells alone when peripheral blood mononuclear cells (PBMCs) from HAM/TSP cases were treated with TKIs. Treating the PBMCs with nilotinib or dasatinib induced significant reductions in PVL (21.0% and 17.5%, respectively) in live cells. Furthermore, ABL1 siRNA transfection reduced cell viability in HTLV-1-infected cell lines, but not in uninfected cell lines. A retrospective survey based on our clinical records found a rare case of HAM/TSP who also suffered from CML. The patient showed an 84.2% PVL reduction after CML treatment with imatinib. We conclude that inhibiting the ABL1 tyrosine kinase specifically reduced the PVL in PBMCs from patients with HAM/TSP, suggesting that ABL1 is an important gene for the survival of HTLV-1-infected cells and that TKIs may be potential therapeutic agents for HAM/TSP.

Human Blood-Brain Barrier Disruption by Retroviral-Infected Lymphocytes: Role of Myosin Light Chain Kinase in Endothelial Tight-Junction Disorganization

The blood-brain barrier (BBB), which constitutes the interface between blood and cerebral parenchyma, has been shown to be disrupted during retroviral associated neuromyelopathies. Human T cell leukemia virus (HTLV-1)-associated myelopathy/tropical spastic paraparesis is a slowly progressive neurodegenerative disease, in which evidence of BBB breakdown has been demonstrated by the presence of lymphocytic infiltrates in the CNS and plasma protein leakage through cerebral endothelium. Using an in vitro human BBB model, we investigated the cellular and molecular mechanisms involved in endothelial changes induced by HTLV-1-infected lymphocytes. We demonstrate that coculture with infected lymphocytes induces an increase in paracellular endothelial permeability and transcellular migration, via IL-1alpha and TNF-alpha secretion. This disruption is associated with tight junction disorganization between endothelial cells, and alterations in the expression pattern of tight junction proteins such as zonula occludens 1. These changes could be prevented by inhibition of the NF-kappaB pathway or of myosin light chain kinase activity. Such disorganization was confirmed in histological sections of spinal cord from an HTLV-1-associated myelopathy/tropical spastic paraparesis patient. Based on this BBB model, the present data indicate that HTLV-1-infected lymphocytes can induce BBB breakdown and may be responsible for the CNS infiltration that occurs in the early steps of retroviral-associated neuromyelopathies.

Involvement of p38 MAPK signaling pathway in IFN-γ and HTLV-I expression in patients with HTLV-I-associated myelopathy/tropical spastic paraparesis

We analyzed the relationship between the expression of interferon (IFN)-gamma and HTLV-I p19 antigen and activation of p38 mitogen-activated protein kinase (p38 MAPK) in two HTLV-I-infected T cell lines derived from two patients (HCT-1 and HCT-4) with HTLV-I-associated myelopathy/tropical spastic paraparesis (HAM/TSP), and three HTLV-I-infected T cell lines derived from three patients with adult T cell leukemia (ATL). Expression of phosphorylated (activated)-p38 MAPK was markedly increased concomitant with high levels of both IFN-gamma and HTLV-I p19 antigen expression in both HCT-1 and HCT-4 compared with cell lines derived from ATL patients. Treatment with SB203580, a specific inhibitor of p38 MAPK, suppressed IFN-gamma and HTLV-I p19 antigen expression levels in HCT-1, HCT-4 and peripheral blood CD4(+) T cells of HAM/TSP patients. These findings strongly suggest that activation of p38 MAPK signaling pathway is involved in the up-regulation of IFN-gamma expression with high HTLV-I proviral load in HAM/TSP patients.

Longer dinucleotide repeat polymorphism in matrix metalloproteinase-9 (MMP-9) gene promoter which correlates with higher HTLV-I Tax mediated transcriptional activity influences the risk of HTLV-I associated myelopathy/tropical spastic paraparesis (HAM/TSP)

Matrix metalloproteinase-9 (MMP-9) has been reported to be expressed in various inflammatory disorders including human T cell lymphotropic virus type I (HTLV-I) associated myelopathy/tropical spastic paraparesis (HAM/TSP). HTLV-I-infected T-cells expressed high levels of MMP-9 via viral transactivator Tax mediated activation of the MMP-9 promoter. To investigate whether the d(CA) repeat polymorphism in MMP-9 promoter affects the risk of developing HAM/TSP, we compared the allele frequencies between 200 HAM/TSP patients and 200 HTLV-I seropositive asymptomatic carriers (HCs). The longer d(CA) repeat alleles of MMP-9 promoter, which was associated with higher Tax-mediated transcriptional activity, was more frequently observed in HAM/TSP patients than HCs (p<0.01 by Mann-Whitney U-test). The length alteration of this d(CA) repeat in the MMP-9 promoter may cause phenotypic differences among HTLV-I infected infiltrating cells and may thereby be in part responsible for the development of HAM/TSP.

Selective matrix metalloproteinase inhibitor, N-biphenyl sulfonyl phenylalanine hydroxamic acid, inhibits the migration of CD4+ T lymphocytes in patients with HTLV-I-associated myelopathy

Matrix metalloproteinases (MMPs) have been reported to be involved in various inflammatory disorders. Previous studies revealed that MMP-2 and MMP-9 might play important roles in the breakdown of the blood-brain barrier (BBB) in the central nervous system (CNS) of patients with HTLV-I-associated myelopathy (HAM)/tropical spastic paraparesis (TSP). N-Biphenyl sulfonyl-phenylalanine hydroxamic acid (BPHA) selectively inhibits MMP-2, -9 and -14, but not MMP-1, -3 and -7. In the present study, we examined whether or not the selective MMP inhibitor BPHA could inhibit the heightened migrating activity of CD4+ T cells in HAM/TSP patients. The migration assay using an invasion chamber showed that migration of CD4+ T cells in HAM/TSP patients was inhibited by 25 microM BPHA. In addition, the inhibitory ratio of migrating CD4+ lymphocytes was higher in HAM patients compared to normal controls. These results suggest that the selective MMP inhibitor BPHA has therapeutic potential for HAM/TSP.

[Increased activity of metalloproteinases and their inhibitors in cerebrospinal fluid of patients with tropical spastic paraparesis]

BACKGROUND

Proteolytic modifications of neuronal surfaces and the surrounding extracellular matrix are very important in neuronal development and regeneration. Increased activity of matrix metalloproteinases (MMPs) and their tissue inhibitors, due to secretion by macrophages and lymphocytes, occur in inflammatory processes that disrupt the blood brain barrier. However, neurons and microglia can also secrete these enzymes.

AIM

To identify the type of MMP present in the cerebrospinal fluid (CSF) and changes in the expression of tissue inhibitors of metalloproteinases (TIMPs) in patients with HTLV-1 associated tropical spastic paraparesis.

PATIENTS AND METHODS

CSF samples from 12 patients with HTLV-1 associated tropical spastic paraparesis and 12 healthy controls were obtained by an atraumatic lumbar puncture. The presence of MMPs was measured by zymography and the relative amounts of TIMPs were measured by immunowestern blot.

RESULTS

In the CSF of both controls and patients, a similar gelatinolytic band corresponding to proMMP-2 (latent form) was observed. In 83.3% of patients with HTLV 1 associated tropical spastic paraparesis, the MMP-9 was also present. TIMP-1, TIMP-2 and TIMP-3 were elevated 2.24 +/- 0.72, 3.85 +/- 1.38 and 5.89 +/- 3.4 fold, respectively, in the CSF of patients as compared to controls.

CONCLUSIONS

Patients with HTLV-1 associated tropical spastic paraparesis have elevated activity of MMP-9 and levels of TIMPs in the CSF, when compared to healthy controls.

T lymphocytes activated by persistent viral infection differentially modify the expression of metalloproteinases and their endogenous inhibitors, TIMPs, in human astrocytes: relevance to HTLV-I-induced neurological disease

Activation of T lymphocytes by human pathogens is a key step in the development of immune-mediated neurologic diseases. Because of their ability to invade the CNS and their increased secretion of proinflammatory cytokines, activated CD4+ T cells are thought to play a crucial role in pathogenesis. In the present study, we examined the expression of inflammatory mediators the cytokine-induced metalloproteinases (MMP-2, -3, and -9) and their endogenous inhibitors, tissue inhibitors of metalloproteinases (TIMP-1, -2, and -3), in human astrocytes in response to activated T cells. We used a model system of CD4+ T lymphocytes activated by persistent viral infection (human T lymphotropic virus, HTLV-I) in transient contact with human astrocytes. Interaction with T cells resulted in increased production of MMP-3 and active MMP-9 in astrocytes despite increased expression of endogenous inhibitors, TIMP-1 and TIMP-3. These data suggest perturbation of the MMP/TIMP balance. These changes in MMP and TIMP expression were mediated, in part, by soluble factors (presumably cytokines) secreted by activated T cells. Integrin-mediated cell adhesion is also involved in the change in MMP level, since blockade of integrin subunits (alpha1, alpha3, alpha5, and beta1) on T cells resulted in less astrocytic MMP-9-induced expression. Interestingly, in CNS tissues from neurological HTLV-I-infected patients, MMP-9 was detected in neural cells within the perivascular space, which is infiltrated by mononuclear cells. Altogether, these data emphasize the importance of the MMP-TIMP axis in the complex interaction between the CNS and invading immune cells in the context of virally mediated T cell activation.

[A study of free radical defense and oxidative stress in the sera of patients with neuroimmunological disorders]

Free radicals are molecules that contain at least one unpaired electron and by nature are highly reactive and potentially destructive. Free radical damage can play an important role of demyelination. Glutathione peroxidase, which plays a role in free radical defenses, and myeloperoxidase and lactoferrin, which are considered to reflect the strength of oxidative stress, were examined by monoclonal antibody-based enzyme immunoassay on serum samples taken from patients with neuroimmunological disorders, namely, 35 multiple sclerosis(MS), and 2 Baló disease, 10 Guillain-Barré syndrome(GBS), and 25 human T-lymphotropic virus type-1 associated myelopathy (HAM). The levels of glutathione peroxidase in active phase of MS (8.37 +/- 5.59 micrograms/ml: p < 0.05) were increased rather than in inactive phase (5.05 +/- 2.44 micrograms/ml) and control (5.41 +/- 1.40 micrograms/ml), the levels of myeloperoxidase in HAM (95.5 +/- 89.1 ng/ml: p < 0.05) were increased rather than in controls (21.5 +/- 4.1 ng/ml), and the levels of lactoferrin were not significantly increased than in other disease and control. Moreover the levels of myeloperoxidase and lactoferrin are increased in Baló disease (myeloperoxidase 487, 762 ng/ml; not significant, lactoferrin 2.58, 2.77 ng/ml; not significant) than in control (myeloperoxidase 21.5 +/- 4.1 ng/ml, lactoferrin 0.69 +/- 0.32 ng/ml). In conclusion, we have here first demonstrated that the levels of these enzyme were not paralleled in MS and Baló diseases. In GBS the levels of all these enzyme were not increased. Thus, these findings suggest that these enzyme may play an important role of the disease activity of Baló, and may reflect the activity of the defense of MS.

Serum deoxythymidine kinase in adult T-cell leukemia-lymphoma and its related disorders

Serum deoxythymidine kinase (TK) was measured in 15 patients with the acute type of adult T-cell leukemia (ATL), in 4 with chronic ATL, in 10 with lymphoma type ATL, in 9 with pre-ATL, in 11 with human T-cell leukemia virus type I (HTLV-I) associated with myelopathy (HAM) and in 19 HTLV-I carriers. All these patients were positive for anti-HTLV antibody. The level of TK in pretreatment serum was highest in acute ATL (15.6-1600 U/l, median 107 U/l). It was elevated in chronic ATL (5.4-55.0 U/l, median 37.6 U/l) and lymphoma ATL (6.8-316 U/l, median 16.8 U/l) but normal in pre-ATL (1.8-4.7 U/l, median 2.8 U/l), HAM (1.2-6.0 U/l, median 3.0 U/l) and HTLV-I carriers (1.1-4.6 U/l, median 2.3 U/l). Statistical examination revealed a significant difference between the levels of acute ATL and chronic ATL/lymphoma ATL. In the patients of this series, a close correlation between the level of TK and lactic dehydrogenase (LDH) was statistically present (p less than 0.01). These facts indicate that TK level is a useful indicator of the aggressiveness of ATL cells.